Experimental irritant contact dermatitis due to cumulative epicutaneous exposure to sodium lauryl sulphate and toluene: single and concurrent application

In clinical practice, cutaneous exposure to a variety of irritants such as surfactants and solvents is frequent. Although the induction of irritant de rmatitis by single irritants has been extensively studied in recent years, our knowledge of the effects of simultaneous application of different irrit ants is limited. Using non-invasive techniques for measurements of transepi dermal water loss (TEWL) and skin colour reflectance, we quantified the irr itant effects of single and concurrent application of 0 . 5% sodium lauryl sulphate (SLS) and undiluted toluene (TOL) in vivo. The irritants were appl ied twice daily for 30 min to the volar forearms of 20 volunteers. Repeated application of SLS and TOL induced an irritant reaction, as indicated by a n increase in TEWL and skin redness. In contrast to SLS alone, the applicat ion of TOL alone induced only a moderate increase in TEWL, confirming previ ous results. Concurrent application of SLS/TOL and TOL/SLS induced signific antly stronger reactions than those caused by twice daily application of ea ch irritant on its own. Our results demonstrate that a mixed application of an anionic detergent and an organic solvent has an additive effect on skin irritation. It is suggested that pretreatment with SLS causes an increased susceptibility to TOL irritation and vice versa. Thus, the necessity for s pecial precautions against skin absorption of TOL when handling detergents such as SLS is emphasized.